236. THE ENTOMOLOGIST. 



about ten clays, but I am glad to say that now only a few- 

 stragglers remain. 1 do not think I exaggerate when I say 

 that there must have been thousands of thera in my room 

 where I was performing some operations with canlharides. 

 If you can tell me anything of their history, and where they 

 are likely to have come from, I shall be greatly obliged by 

 your doing so. 



[The fly is unquestionably Musca pluvialis; but with 

 regard to their economy I have to confess my entire igno- 

 rance, and shall be obliged for information. I have not only 

 heard of, but known, instances of flies assembling indoors in 

 such large numbers, but I cannot find out the attraction, or 

 what it is that induces a line of conduct apparently so much 

 at variance with their general habits. — Edward New77ian.] 



T. R. Archer Briggs. — Gall on Poienlilla reptans. — I en- 

 close specimens of another gall from the neighbourhood of 

 Plymouth, and shall be very glad to know the name of it, 

 although it may prove to be but a common one. I found it 

 on the 30th of August, in a pasture in the Tavy Valley, near 

 Plymouth, Devon, occurring, as you will see, on the stems 

 and petioles of the creeping cinquefoil (Potentilla reptans). I 

 do not remember to have noticed it previously. 



[Mr. Fitch kindly hands me a reply, as under : — " I believe 

 this gall is included, both by Marshall and Mtiller, under 

 Curtis's name of Brevicornis, which is probably a synonym 

 of Aulax Potentillae of Hartig; or, as Foester has it, Xesto- 

 phanes Potentillae de Villers = Aulax splendens of Hartig." 

 — E. A. Fitch.] 



Joseph Anderson, jtin. — Effect of Acids on Green Insects. 

 — I have in my cabinet a foreign beetle resembling a 

 gigantic specimen of Aroraia Moschata. The name of it is, I 

 believe, Golofa Porteri, and it should be a brilliant green 

 colour; but one day, thinking to "kyanise" it, I saturated it 

 with phenic acid, and was mortified by seeing it change to a 

 coppery red. Could you, or any of your correspondents, tell 

 me of an alkali that would be likely to restore the original 

 colour ? 



[The eff'ectof acid on the colours of insects is so great that 

 it is better to avoid the use of them altogether. In the case 

 of metallic colours it is less observable than in the delicate 

 wings of Lepidoptera. 1 cannot mention any drug trom 



